The ability to steer or to controllably direct the path or the trajectory of a beam of radiant electromagnetic energy is a significantly useful tool in numerous radiant electromagnetic energy-based modern systems. Indeed, such ability to steer the travel direction of energy beams can be argued to be as significant in their utility as the underlying ability to place energy in these forms. Reflection of radiant energy in one or more manners has been known since the earth began and was perhaps first humanly experienced when a primitive man found light and heat from the sun was redirected by the smooth surface of a water body or from some naturally occurring objects such as a polished rock. In more modern times, the reflection of radio frequency spectrum energy from a metallic surface such as a reflector or from the surface of some object such as an aircraft or from moisture in a rain cloud has become the basis for radar systems of large variety. The use of metals as an energy reflection element across large portions of the electromagnetic spectrum has become a common event in environments as diverse as the electrical heater and the parabolic reflector used for electrical and optical signal enhancements.
The wide spectral extent of these radiant energy reflection characteristics are particularly notable and are relevant to the present invention. In terms of wavelength, radiant energy reflections are found to be especially useful in wavelengths extending from multiple centimeters as occur in the microwave portion of the radio frequency spectrum through the wavelengths measuring in microns as exist in the optical spectrum. Although the apparatus used to accomplish useful reflections in these diverse parts of the electromagnetic spectrum may differ significantly in physical arrangement it is possible to consider common principles applicable throughout this range of wavelengths and to speak of the generic concepts included in devices intended for more limited portions of this wavelength range in describing phenomenon occurring in the present invention. The optical end of this spectral range and energy steering accommodations made there may be considered first in approaching this broad spectral range.
Current liquid crystal and Microelectromechanical Deformable Micromirror (MEMS-DM) technologies do not for example offer the required ninety to one hundred twenty degree steering angles needed for effective optical and infrared beam steering purposes. Infrared radiation is however currently used for example in high fidelity sensing and is needed to deliver high energy to target objects at wide angles. Furthermore, present day agile beam-steering technologies for these wavebands or smaller can not operate in the high power/high energy environments needed for many projected military and non military uses expected in this spectral region with for example an infrared laser. Moreover inertia-free or electronically steered arrays, with characteristics needed for these uses in both the radio frequency and infrared applications have not heretofore been developed.
The use of energized or ionized gaseous plasma for video image display purposes has now become familiar in the electronic art. Devices of this type find utility in for example applications such as illuminated computer and television displays, large ballpark and stadium displays and aircraft instrumentation. Several of the prior art patents identified in the present document in fact use emissions from such gaseous plasma to stimulate phosphor transducer materials into emission of selected output wavelengths to provide a multicolor capable display. Interestingly, some of these herein identified patents also note a degree of similarity between plasma displays and the liquid crystal display that is frequently employed in lower energy applications such as battery powered watches and handheld electronic calculators for example. For present purposes, however, it appears significant to consider that such usage of ionized gas plasma in display oriented applications has heretofore largely ignored the capability of similarly disposed plasma to perform radiant energy steering functions.
Thus such plasma, when present in sufficient density, is found to have the ability to refract, radiate, absorb, transmit, and reflect electromagnetic wave energy over a wide range of radiant energy wavelengths and is seen as a possible answer to presently incurred radiant energy steering limitations. Infrared radiation in the electromagnetic wavelength spectrum from for example 0.4 micrometer to 12.5 micrometers is considered in the present invention. Along with this spectral range the arrangements of the invention are believed also usable in the radio frequency spectrum, in the microwave region for example.